Engine piston



Feb. 8, 1938. E. P. LARsH 2,107,795

ENGINE P I STON Filed Nov. 15, 1935 Patented Feb. 8, 1938 i n I UNITED STATES PATENT OFFICE v ENGINE PISTON Everett Pv. Larsh, Vandalia, Ohio, assignor p to' f The Master Electric Corporation, Dayton, Ohio,

a corporation of Ohio Application November 15, 1935, Serial No. 49,988

21 Claims. (Cl. 309-20) This invention relates to engines and more A further object of th'e invention is to provide '1 particularly to engine' pistons and connecting a. piston head which will be uniformly susceprods. tible to expansion and contraction under varia- While it is recognized that a ball and socket tions of temperature, and hence at all times ac type of universal connection between a piston curately fitting the cylinder. 5

head and its connecting rod is broadly quite old A further object of the invention is to proand well known in this art, the present invention vide a thrust bearing of relatively large size, the pertains to structural features and arrangement parts of which may be conveniently and inexof parts which adapt such type of construction pensively manufactured by present production l0 to present day needs and economies of commermethods and which may be readily assembled l0 cial production. The ball and socket type of conand disassembled by unskilled' mechanics. nectionA possesses some inherent fundamental A further object of the invention is to provide advantages which render it especially desirable an improved; form of connecting rod of hollow for high compression engines of the hydro-,cartubular construction and to provide a hollow bon fuel type andespecially for Diesel style enspherical head therefor adaptable for modern l5 gines. mass production methods.

The usual wrist pin type of piston and con- A further object of the invention is to provide necting rod assembly necessitates unequal disimproved detent means for holding the thrust tribution of material throughout the piston head bearing parts in assembly.

in order to provide bearing lugs for the pin of Afurther object of the invention is to provide 29 ample size. As usually constructed such piston an improved crank shaft bearing construction heads embody relatively large masses of material adaptable for multiple radial connecting rods opat diametrically opposite points. Such unequal erating in Substantially a Single Pianedistribution 0f metal not only materially in- A further object 0f the invention iS to Provide creases the weight of the piston head but also a piston and connecting rod assembly possessing 25 causes unequal expansion and contraction under the advantageouastrnetllral features, and merithermal change necessitating in some instances torious characteristics herein mentioned.

that-the piston be made eccentric or out of round A further object of the invention 1s to provide so that as it unequally expands underA increase an'improved method of production of piston Conof temperature it may assume true cylindrica nteeting rod Darts and method of assembly there- 30 Furthermore in the use of the customary wrist With the above primary and other incidental vpin type of connection, the lthrust pressure is obieotS in-VieW aS Will more fully appear in the concentrated upon a relatively small surface of Speoioation. the invention1 consists of the feathe pin transversely of the piston head whereas -tureS 0f Construction, the Darts and oombina- 35 the present ball and socket type of connection tions thereof, the mode of operation or their aords a relatively large concentric area, over equivalents as hereinafter described and set forth" which the thrust pressure is .uniformly distribin the olaimS- l uted in equalized relation with the piston. Referring to the drawing wherein iS Shown the As heretofore constructed ben and socket type preferred. but obviously not necessarily the only 4o v piston and connecting rod assemblies have been formof embodiment 0f the invention, Fig. 1 is a expensive and difficult to accurately manufacture longitudinal Sectional View of a Piston and oonin quantity production. They have heretofore necting rod assembly. Fig.l 2 is a side elevation also involved diiiicult problems of assembly and partly in Section of the Crank Shaft bearing P01- maintenance. -tions'of a group of radial connecting rods. Fig. 3 M

The present construction is designed to overis a plan view of a' shim which may be employed come the existing objections lto ball and socket to produce conformity between the connecting type of piston and connecting rod assembly while rod head and the socket therefor. Fig- 4 iS an retaining the advantageous features thereof. elevation of the shim shown in Fig. 3.

" The object of the invention is to improve the vLike parts are indicated by similar characters 50 .55 durability, and unlikely to need repair.

construction of engine piston and connecting rod of reference throughout the several views. assemblies whereby they may not only be eco- Referring to the drawing, i is lthe piston head nomically manufactured, but will be more-el the cylindrical walls of which are circumferencient in use, of maximum strength and increased tially` of uniform thickness, although of varying thickness longitudinally. Such piston head will 55 tend to expand and contract uniformly. The piston head is provided with the usual sealing rings 2 seated-in peripheral grooves. 'I'he piston head I is provided at midlength with an internal rab-` bet formed by a shoulder 3. Seated against the shoulder 3 is a semi-spherical socket member 4, having a peripheral flange 5 engaging the shoulder 3. Ihis socket member is stamped from sheet metal of suitable thickness and strength. The thickness and strength of the material may vary according tothe conditions of use and size and capacity of the engine andv developed pressures to which the piston is subjected. The thrust bearing provided by the socket member 4 is substantially equal to the internal diameter of the piston head I. Associated with the member 4 is a complementary socket member 6 of annular truncated spherical form. also provided with an annular flange 1 extending within 'the internal rabbet in proximate relation withthe flange 5 of the socket member 4. Interposed between the bearing members 4 and 6 is the hollow spherical head 8 of a tubular connecting rod 9.

'Ihe skirt of the piston head I is' provided with a helical groove I0 beneath which the piston skirt is tapered or flaring as at II. The helical groove I0 leads into an internal planar groove I2 of i somewhat greater depth than the helical groove I2. This ring is insertable therein by a screwingaction through the helical groove I0. By forcing the split ring into the tapered extremity I l of the piston skirt it is diametrically contracted suinciently to enter the helical groove I0 wherein it will assume a corresponding helical shape with its ends in slightly overlapping relation. In' such condition it may be rotated within the helical groove until it passes therefrom intol the' planar groove I2. This groove being of greater depth, the ring will expand therein with a snap action and will retain its position thereiny to prevent displacement of the socket members 4 and 5. l

These socket members conform accurately to the spherical headv of the connecting rod, but are so proportioned that their flanges 5 and 'I do not f vconnecting rod bearing `oi? lubricant supplied through radial oil ducts I4. To insure that the socket members shall conform at all times to the sary are interposed between the retaining 'ringA normally contact, but are separated by a, small clearance space which permits the socket member 6 to conform closely to the head .of the connecting rod. 'I'his space also permits entrance to the connecting rod head, shims I3a as may be neces- I3 and the flange 1 of the annular socket member. In lieu' of shims a corrugated spring collar as shown in Fig. 3 may be utilized. I'he resiliency of such spring collar will automatically compensate for wear and insurey a close fit of the connecting rod head in its'socket bearing at all times.

AThe connecting rod 3 is of tubular material,

one end of which is expanded into semispherical shape to form an integral portion of the connecting rod 8. Welded to such expanded extremity of the tubular connecting rod is asemi-spherical cap portion which completes* the head 8 of' the.v

connecting-rod. This spherical extremity is accurately ground tosize lto fit the socket members 4 and 6. At its .opposite end the tubular connecting rod may be formed with the conventional annular split head to iit the crank shaft-bear- -receive the ends of such springs.

2,107,795 Y ing'. However in the drawing the connecting rod is shown provided with a segmental bearing shoe Il to which thetubular stem is welded.

As shown in Fig: 2 the segmental bearing shoe enables multiple connecting rods to be connected with the same crank shaft bearing for operation in the same plane. This is of especial advantage in engine designs embodying .radially disposed multiple cylinders.

The crank shaft bearing shoes I5 are preferable forgings each of which includes a shank portion I6 extending'within the end of the tubular rod nectingrod shoes are held in assembled relation about the crank shaft by recessed collars I3, preierably of bronze, disposed on opposite sides of the several connecting rods. The inner sides of the recessed retaining rings extend intermediate the crank shaft and the connecting rod shoes from opposite sides and aord in effect a bushing for the assembly of connecting rods within which the crank shaft I1 rotates.

'I'he outer sides of the recessed retaining rings y overhang the opposite beveled outer faces of the shoes I5 and holdthe several rods in operative relation with the crank shaft. The crank shaft rotates within the rings I8, but the rods have a limited to and fro movement circumferentially of the rings and relative to each other as the several connecting rods reciprocate and the crank shaft rotates.

To maintain substantially equal spacing of the several connecting rods, helical springs I3 maybe interposed between the adjacent bearing shoes I5 which are provided with sockets or seats 20 to In the event the engine is provided with force feed lubrication, an oil conduit 2| may be axially supported within the tubular connectingv rod by spacer collars 22.

The tubular conduit 2I communicates with a passage 23 in the bearing shoe I5 through which oil is conducted from the crank shaft bearing. At its upper end the oil conduit 2| communicates with the interior of the spherical head 8 which may be provided with Lsmall oil ports through which oil may be supplied to the connecting rod head` bearing in the socket members 4 and 6.

The helical groove I0 of the vpistonhead is preferably, although not necessarily of gradually increasing. depth merging at its outerend with the surface of the flaring interior of the skirt portion and merging at its inner end into the planar groove I2. 'I'he radial expansion of the split ring I3 as it passes under tension through the helical groove and into the planar groove effectively prevents its return movement while in use.

thereof vat the split downwardly into helical form and entering it into the contiguous portion of the helical-groove, whereupon the ring may be rotated under compressive tension by an unscrewing movement through the groove I0 into the outer flaring portion of the piston head. Such lflare of the piston skirt conveniently enables initial compression of the expansible split ring sumciently to enter it into the helical groove I0. This construction affords a highly eilicient means for retaining the parts in assembly, but which Imay be economically manufactured and quit readily installed and removed. t f From the above description it will be. apparent 15h84; there i8 thus provided a device of the char- The I ring may be readily removed by drawing one end acter described possessing the particular features of advantage before enumerated as desirable, but

, fore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

, Having thus described my invention, I claim:

l. A hollow piston head open at one end, the interior of the open end being tapered, an internal circumferential rabbet therein, an internal circumferential planar groove therein, spaced from the rabbet toward the open end of the piston head, and an internal helical groove leading from the internal tapered area to the internal circumferentialplanar groove. n

2. In an engine piston, a hollow piston head including a skirt portion, a circumferential rab- -bet withlnthe skirt portion of the piston, an internal circumferential groove in the head in spaced relation with the rabbet, a split retaining ring seated in the groove, a pair of reversely arranged concentric hollow spherical bearing members including peripheral flanges interposed between the retaining ring and rabbet, one of the bearing members being truncated. a connecting rod including a spherical head enclosed between the spherical bearing members, a helical groove interiorly of the skirt portion of the piston head of less depth than the retaining ring groove leading thereto, the skirt of the piston head being interiorly taperedfcontinguous to the entrance end of'the helical groove.

` 3. In an engine piston, a hollow piston head including a skirt portion, an internal circumferential rabbet in such skirt portion, a planar groove inv spaced relation with the rabbet, a pair of hollow spherical bearing members concenf trically arranged in reverse relation the diameters of which are substantially equal to the interior diameter of the hollow piston, one of which is truncated, peripheral flanges on the spherical bearing members overhanging the internal rabbet, retaining means engageable with the planar groove for removably securing the bearing members in assembled relation with the piston head, a connecting rod and a spherical head therefor enclosed between the bearing members.

4. The combinationwith a hollow piston head and a connecting rod having a spherical head, of a pair of complementary hollow spherical bearing members, one of which `is truncated, of uniform r cluding a hollow piston head having walls of substantially uniform mass peripherally, whereby the head will have substantially uniform expansion and contraction in response to thermal change, a concavo-convex semi-spherical diaphragm peripherally engaged with the piston head walls and forming a thrust seat for a connecting rod, a connecting rod including a spherical head seated within the concavo-convex diaphragm, a concavoconvex retaining collar of truncated spherical form peripherally engaged with the piston head walls in opposing relation with the spherical dlaphragm and maintaining the connecting rod head therebetween, a planar groove within the piston, and a retaining ring engageable therewith and withthe retaining collar for maintaining the diaphragm and the retaining collar in assembly.

6. As an article of manufacture, la piston, a bearing socket therein including a substantially semi-spherical bearing member of substantially uniform thickness throughout, including a planar peripheral flange formed integral therewith, and a complementary bearing member comprising a collar of truncatedspherical shape of substantially uniform thickness throughout having a planar peripheral flange formed integral therewith, said members coacting to form a bearing socket, a ball headed connecting rod engageable therein, a planar groove inthe piston head in which the planar peripheral flanges of the bearing members are disposed in operative position, and a ring member engageable in the planar groove to retain the parts in assembled relation.

'1. As an article of manufacture, a hollow piston head having -an interiorly flaring skirt portion, an internal circumferential rabbet in spaced relation with the flaring skirt portion, an internalV circumferential planar groove in spaced relation with the rabbet, and a helical groove leading from the flaring skirt portion to the internal circumferential groove, a bearing member removably positioned between the rabbet and groove, and a retaining ring engageable inthe groove for securing the bearing members and a connecting rod including a head engageable in said bearing members.

. 8. In combination, a hollow piston head open at one end, an internal circumferential rabbet and an internal circumferential planar groove therein, the groove being spaced from the rabbet toward the open end of the piston head, an interpiston head, a removable connecting rod bearing ywithin the head, a retaining member therefor introducible through the helical groove into the planar groove for cooperation with the rabbet as a connecting rod bearing holding means, and a connecting rod engageable in said bearing.

9. Incombination, a hollow piston head open at one end, an internal circumferential planar groove therein, an internal helical groove leading from the circumferential planar groove toward the open end ofv the piston head, a removable connecting rodbearing within the head, a retaining member therefor introducible through the helical groove into the planar groove,and'a connecting rod engageable in said bearing.

10. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, an internal helical groove leading from the circumferentialplanar groove toward the open end of the piston head, a. removable connecting rod bearing including complementary semi-spherical connecting rod bearing shells, a

v retaining member thereforl introducible through the helical groove into the planar groove, and a connecting rod engageable in said bearing.

11. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, an internal helical groove lead- -ing from the circumferential planar groove toward the open end of the piston head, a removable connecting rod bearing including `comple- Vmentary semi-spherical connecting rod bearing shells, a split ring retaining member therefor introducible throughthe helical'groove into the planar groove, and a connecting rod engageable in said bearing. n'

l2. In combination, a hollow piston head ope at one end, an internal circumferential planar groovetherein, an internal helical groove lead- `ing from the circumferential planar groove toward the open. end of the piston head, a removable connectingrod lbearing including complementary semi-spherical connecting rod bearing shells or uniform thickness throughout, o. retaining member therefor introducible through the helical groove into the planar groove, and a connecting rod engageable in said bearing.

13. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, an internal helical groove leading from the circumferential planar groove towardthe open end of the piston head, a removable connecting rod bearing including complementary semi-spherical connecting rod bearing shells of uniform thickness throughout, and ,one

. of whichiis truncated, a retaining `member therefor introduclble through the helical groove into the planar groove, and a connecting rod engageable in said bearing.

14. In combination, a hollow piston head open o between the bearing shells.

l5. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein. an internal helical groove leading from` the circumferential planar groove toward the open end ofthe piston head, a removable connecting-rod bearing including complementary semi-spherical connecting rod bearing shells of uniform thickness throughout, a retaining member therefor introducible through the helical groove into the planar groove, and a 16. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, an internal helical groove leading from the circumferential planar groove toward the open end of the piston head. a removable spherical socket forming a connecting rod bearing, a retaining member therefor introducible through the helical groove into the planar groove, and a tubular connecting rod havingwa hollow spherical head engageable in the socket.

17. In combination, a hollow piston head'open at one end, an internal circumferential planar groove therein, a removable connecting rod bearing within the head, a collapsible and expansible retaining member therefor engageable in the" planar groove', and a connecting rod engageablev in said bearing. o

' 18. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, a removable connecting rod bearing within the head, a collapsible and expansible split ring retaining member therefor engageable in the planar groove, and a connecting rod en-.

gageable in said bearing.. y

19. In combination, a hollow piston head open at one end, an internal circumferential planar groove therein, a removable connecting rod bearing within the head, a collapsible and expansible retaining member therefor engageable in the planar groove, and a tubular connecting rod having a hollow Aspherical head ehgageable inthe bearing. l

20. In combination, a hollow piston head open at one end, an internalcircumerential planar groove therein, a removable connecting rod bearing including complementary semi-spherical bearing shells, a collapsible yand expansible retaining member therefor engageable in the planar groove, and a tubular connecting rod having a hollow spherical head engageable betweenthe i0 connecting lrod bearing shells.

2l. In combination, a hollow piston head open `at one end, an internal circumferential planar groove therein, an internal helical groove leading from the'clrcumferential vplanar groove toward the open end of the pistonvhead, apair of semi-spherical bearing-shells having integral flat flanges thereon, a bearing ledge within the piston against which the flange of one of the bearing shells abuts, the flange of the other bearing shell being adapted to lie concentric to the flange of the first named bearing shell, a retaining member introducible through the helical groove for retaining the flange oi one bearing shell in abutting relationwithxthe ledge and the 'harigel of the other shell in juxtaposed concentric relation therewith, and a ,connecting rod engageable in Said bearing.

60' turmoiconnecting rod having o. hollow spherical o o P. Lansn. u head engageable between the bearing shells. 

